Thermal expansion behavior of SrSiO3 and Sr2SiO4 determined by high-temperature X-ray diffraction and dilatometry

2015 ◽  
Vol 50 (16) ◽  
pp. 5533-5539 ◽  
Author(s):  
Christian Thieme ◽  
Christian Rüssel
2010 ◽  
Vol 12 (3,4) ◽  
pp. 241 ◽  
Author(s):  
M.V. Sukhanov ◽  
I.A. Schelokov ◽  
V.I. Pet'kov ◽  
E.R. Gobechiya ◽  
Yu.K. Kabalov ◽  
...  

<p>New phosphates MNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> (M = Mg, Ca, Sr) were prepared by the precipitating method.<strong><em> </em></strong>Phosphates were characterized using X-ray powder diffraction, IR-spectroscopy and electron microprobe analyses. The crystal structure of phosphates was refined by the Rietveld method. Phosphates CaNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> and SrNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> are shown to have been crystallized in the NaZr<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub>-type structure and the phosphate MgNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3 </sub>was obtained as a single-phase with Sc<sub>2</sub>(WO<sub>4</sub>)<sub>3</sub>-type structure. Heat capacity of phosphate CaNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> was measured in the range 7 – 650 K and increased monotonically over the entire temperature range studied. Thermal expansion of phosphate CaNi<sub>0.5</sub>Zr<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> was studied in the interval 295-1073 K by the high temperature X-ray diffraction. This phosphate is similar to the best low-expansion ceramics, such as zircon, cordierite and silica glass in thermal expansion behavior.</p>


2017 ◽  
Vol 726 ◽  
pp. 470-477
Author(s):  
Jin Hua Zhang ◽  
Chang Ming Ke ◽  
Hong Dan Wu ◽  
Ji Shun Yu

The hexagonal cordierite was synthesized by the reverse coprecipitation-calcination method and characterized by powder X-ray diffraction. The lattice thermal expansion behavior of hexagonal cordierite was investigated by high temperature X-ray diffraction in the temperature range 298-1273 K. The lattice parameters of the hexagonal cordierite at different temperature were calculated by a least squares method. The hexagonal cordierite expressed anisotropic thermal expansion behavior with the average lattice thermal expansion coefficient were 2.13×10-6 K-1 along a or b axis and-1.03×10-6 K-1 along c axis from room temperature to 1273 K. The crystal structure of hexagonal cordierite at 298 K and 1273 K were refined by Rietveld method. The thermal expansion coefficient of the height of the [MgO6]-[AlO4] polyhedral layer is-1.8×10-6 K-1. Although the six-member ring expressed the normal positive thermal expansion along arbitrary direction, the height thermal expansion coefficient of the six-member ring is just 0.6×10-6 K-1.


2008 ◽  
Vol 93 (17) ◽  
pp. 171912 ◽  
Author(s):  
Guang Mo ◽  
Quan Cai ◽  
Longsheng Jiang ◽  
Wei Wang ◽  
Kunhao Zhang ◽  
...  

2005 ◽  
Vol 20 (2) ◽  
pp. 350-356 ◽  
Author(s):  
Amreesh Chandra ◽  
Dhananjai Pandey ◽  
M.D. Mathews ◽  
A.K. Tyagi

High-temperature dilatometric studies on (Pb1−xCax)TiO3 (x = 0.35, 0.35, 0.40, 0.45) ferroelectric ceramics reveal negative thermal expansion for x ≤ 0.40. The negative thermal expansion coefficient for x = 0.30, as obtained by dilatometry and powder x-ray diffraction, were found to be −8.541 × 10−6 K−1 and −11 × 10−6 K−1, respectively, which are comparable to those of other well-known negative thermal expansion materials like ZrW2O8, NaZr2(PO4)3. Results of temperature-dependent x-ray diffraction studies are also presented to show that the large negative thermal expansion behavior for x = 0.30 persists in a very wide range of temperatures, 70–570 K. Ca2+ substitution reduces the value of the negative thermal expansion coefficient of pure PbTiO3 crystal, but it enables the preparation of strong sintered ceramic bodies. The negative thermal expansion behavior is shown to disappear above the ferroelectric Curie point and is restricted to only the tetragonal compositions of (Pb1−xCax)TiO3.


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